Mechanical calipers or interference measuring probes are used for measuring surfaces in the in the production of mechanical parts, e.g., for measuring the alignment of internal rotational surfaces such as, for example, bores or cones.
Such mechanical or optical measuring probes scan the surface of a workpiece point-by-point. In order to measure one surface or a plurality of surfaces of the workpiece, the measuring probes and the workpiece are moved and aligned in relation to each other, and additional measuring points are scanned in a specific pattern. If the alignment of internal rotational surfaces is to be measured, in the simplest case, two internal surfaces must be scanned, whose position in relation to each other is determined. If interference measuring probes are used for this purpose, the measuring beam must strike the particular test surface orthogonally, and the modulation interferometer on the optical path must be tuned to the particular test surface, i.e., the focal point of the measuring beam must maintain a specific distance from the modulation interferometer if the measuring probe is appropriately positioned on or near the particular test surface.
In particular when surfaces are measured that are not aligned parallel or concentrically with each other, the measuring device is subjected to elaborate modification to ensure that the measuring beam strikes the particular test surface perpendicularly. This necessary modification after measuring a first test surface, also referred to here as a reference test surface, and before measuring a second test surface inclined in relation to it must be done in a highly precise manner in order not to lose the reference to the reference test surface.